1. Field of the Invention
The invention relates to a method for operating a mobile phone device. Particularly, for operating in an environment that has a dynamism with respect to an actual call that comprises transmitting digital information between the device in question and a superior station, which dynamism should mandate in the mobile phone device a mode alteration of the transmitting.
2. Description of the Related Art
Present-day mobile phones are being used for transporting voice as well as digital data, and for transmitting as well as for receiving. In AMPS/NAMPS and TACS/ETACS networks a base station may request a mobile station to tune to another channel. Such other channel may become more preferable than the present one due to various dynamisms, such as a changing distance between the device and the original base station, atmospheric or other interferences, or through still further causes. In practice, when such change occurs during a fax or data call, transmission failures can readily occur that may result in loosing a part of the digital data contained in the fax or data call. It has been proposed to take measures for repairing erroneous or missing data on a relatively high level in the communication, but such will often remain unsatisfactory.
From a call processing point of view, the procedure to establish a call for digital transfer is exactly the same as for a normal voice call; in fact, it would be feasible to have a call that were part voice, part digital. This situation is similar from the point of view of a base station, that does not know whether a mobile station will use a call for voice or rather for data. At present, it appears to be common procedure for effecting data transfer while stopping a motor car that has the portable telephone device on board, which would diminish the dynamism. The invention however, should provides an ultimate block against data losses due to changeover to a different base station.